To study the effects of the spatial distribution of the average wind speed on the aerostatic stability of long-span bridges, the aerostatic stability analysis method considering the spatial distribution of the wind speed was put forward by introducing the wind speed spatial distribution coefficient. By taking the Maanshan Bridge as an example, the effects of the wind speed spatial non-uniformity along the deck on the critical wind speed and the aerostatic instability configuration were analyzed. The results show that the critical wind speed of the aerostatic instability is the lowest when the wind speed is asymmetrically distributed and the maximum wind speed is at the one of the two midspans. When the wind speed is asymmetrically distributed, the torsional and the vertical displacements at the lower wind speeds exhibit the same change tendency. However, the deformations of the span with the higher wind speeds intensify with the increase of the wind speed, and those of the other span change with the opposite trend due to the dragging influence of the main cables. The spatial distribution of the wind speed has a considerable and non-negligible effect on the aerostatic stability of suspension bridges with three towers.